Volumex EFI Conversion?

[chrisc]

As I continue to bring my vx to life for daily usage, ive been contemplating the fuelling system and the nightmares I had on my previous vx, admittedly due to toasted wiring, but hey.

Do you think there would be any point in pursuing a single point injection system for the vx using an aftermarket system? I was thinking it could potentially increase fuel economy, and allow easy fuelling changes as I plan to tweak the engine in future :twisted: as well as also hopefully increasing reliability.

Are there any parts off of later cars I could cannibalise to use in this project? perhaps the fuel injection hf turbos could yield something.

[Will]

.....a 2.5L Buick single TBI with IAC and TPS- I'm not sure if that's what I'll end up using in the final build or not. Solenoid type IAC, so could be adapted to most any aftermarket, MS, etc.

[Wallace]

I can think of two easy-ishways of doing this . . . either a "fuel injection carb body" bolted to the blower in a similar way to a "normal carb" - or weld on individual injector mounts to the inlet manifold.

Pro and cons either way . . . but you'll need some sort of managment system to drive it all.

[chrisc]

I can think of two easy-ishways of doing this . . . either a "fuel injection carb body" bolted to the blower in a similar way to a "normal carb" - or weld on individual injector mounts to the inlet manifold.

Pro and cons either way . . . but you'll need some sort of managment system to drive it all.

I was envisaging the single throttle body attached to the blower with a sensible management system. Multi-port injection would be nice, but I dont see how it could reasonably be done... unless you can tap the injectors into the manifold after the supercharger? im not particularly knowledgable as to whether or not thatd be possible.

[Wallace]

That's the idea . . weld suitable lumps of ally to the manifold on each runner and drill them out to take a standard injector - - but then I suppose you'll need a throtle somewhere as well - so maybe a bit OTT and complicated ! You'd probably have to adjust the duration to take into account the different inlet lengths/restrictions as well . . .

Yep - bad idea . . . try a sinlge throtle body !!! (IMHO)

[Will]

I've already gone through the pros and cons of most of this stuff because I've had three years to think about it, and here are the conclusions I reached (yours may vary, naturally)

Carb-style injector bodies: The problem with these is severalfold. First, you have to have another whole system for idle air control = extra hassle. Second problem is, you are pulling air into both ports of the SC but nothing's to say the actual airflow or pressure is balanced on the other side, or that it'll be even pressure at both ends of the cavity when the SC rotor comes around. Problem? I don't know.
Plus, you now have two of everything- two throttle plates, etc.etc.- you might as well IMO use a smallish 2bbl TBI and save yourself a fistful of cash.
Lastly, and probably most importantly, there's no provision on the things for your correct sensors. The most popular setups require GM sensors, so good luck fitting the TPS, IAC, FPR, etc.etc.!!!

TBI: good but bulky. Has FPR, TPS,IAC and all the goodies in one package, available used CHEEEEAP!!! You can get a used TB with all the sensors in good nick for under $100- cheaper than the sensors alone, new.

Direct port injection: Great, but two issues. Issue number one is space- very limited on the Vx, which forces the injectors to get mounted on a somewhat undesirable angle. You may be able to get around this using side feed injectors and a modified side feed rail, but in any event you'll have plenty of fabrication costs.
Second issue: there's no point in having individual injectors unless you can control them individually. Unless you want to tune the system by swapping out injector sizes, a dauntingly expensive and laborious task, you need a sequential injection system- which will add AT LEAST $400 over a bank-to-bank system in most cases. Plus you need four injectors instead of two, etc.etc. Direct port is nice, but not a) easy or b) cheap, and the benefit over TBI would likely be negligible.

Everybody's got a limit as to what they want to pay for something, so this might not apply to you, but when you hit that point on the curve where it's suddenly $100 per additional HP, I personally would rather take a nice vacation or something. My personal feelings factored in, I'm looking at a TBI system controlled with a cheap aftermarket EFI system. I was looking at the TEC 3, but have been watching the MS for the features I want to be incorporated. This thing is just about at the point that it's "come of age" with $300 assembled units widely available, but still missing some key elements. I like the idea, but may go for the easier to fit TEC or another similar unit. The Motec, Ontronic, Pectel, Emerald, etc- all are a little outside of what I want to spend on my lowly Lancia Scorpion.

Hope when somebody comes along and reads this, they find it helpful. Ciao Lancisti!
-Will

[Wallace]

Idle control's easy ! On the carb/blower plate, screw in a 1/2" union and connect this to a "standard" weber idle control valve (might need a support bracket . ). This is wired to the ECU !

As to the various sensors, - yes - might well be different threads - but not impossible to butcher something up. could run the rpm/tdc sensor direct from the dizzie. After that, it's only air inlet temperature and water temperature to worry about. Can't see the problem with feeding "both ports" of the blower . . . . . the "port" is only a thin bridging piece of ally anyway. . .